1. Field of the Invention
The present invention relates to an apparatus and method for supporting a different system in a broadband wireless communication system using a multi-hop relay scheme. More particularly, the present invention relates to a frame communication apparatus and method for supporting a different system.
2. Description of the Related Art
In a 4th Generation (4G) communication system, which is a next generation communication system, research is being conducted to provide users with services having various Qualities-of-Service (QoSs) at a data rate of about 100 Mbps. In particular, the 4G communication system is evolving to guarantee mobility and QoS for a Broadband Wireless Access (BWA) communication system such as a wireless Local Area Network (LAN) system and a wireless Metropolitan Area Network (MAN) system. An exemplary BWA communication system is a communication system based on the Institute of Electrical and Electronics Engineers (IEEE) 802.16d standard and IEEE 802.16e standard.
The IEEE 802.16d communication system and IEEE 802.16e communication system use an Orthogonal Frequency Division Multiplexing (OFDM)/Orthogonal Frequency Division Multiple Access (OFDMA) scheme for a physical channel.
In a conventional IEEE 802.16e communication system, signaling transmission/reception is implemented through a direct link between a fixed Base Station (BS) and a Mobile Station (MS) and thus, a wireless communication link with high reliability can be easily configured between the BS and the MS. However, in the IEEE 802.16e communication system, because the BS is fixed in position, flexibility in wireless network configuration is low. Thus, it is difficult to provide an efficient communication service in a wireless environment that experiences significant changes in traffic distribution or required calls.
In order to overcome this disadvantage, a fixed Relay Station (RS), a mobile RS, or a general MS is used to apply a multi-hop relay type data forward scheme to a general cellular wireless communication system such as the IEEE 802.16e communication system. The wireless communication system using the multi-hop relay scheme can rapidly adapt to changes in a communication environment, can more easily reconfigure a network, and can more efficiently manage the wireless network. For example, the wireless communication system using the multi-hop relay scheme can extend a cell service area and enhance a system capacity. That is, if a channel state between a BS and an MS is poor, an RS is installed between the BS and the MS, thus configuring a multi-hop relay path through the RS and providing a wireless channel having an improved channel state to the MS. Also, by using the multi-hop relay scheme in a cell boundary area where a channel state from a BS is poor, the wireless communication system can provide a higher-speed data channel, and can extend a cell service area.
The wireless communication system using the multi-hop relay scheme can be, for example, an IEEE 802.16j communication system.
FIG. 1 is a schematic diagram illustrating a construction and frame structure of a conventional IEEE 802.16j communication system.
Referring to FIG. 1, a BS (i.e., a 16 Multi-hop Relay Base Station (16 MR-BS)) can use a relay service of an RS (16j RS) so as to provide a communication service to an MS (16e MS) that is out of its own service area. In order to provide such a relay service, a physical frame structure, indicating if a BS, an RS, and an MS have to transmit/receive data at any time, should be defined.
As illustrated in FIG. 1, a DownLink (DL) subframe and UpLink (UL) subframe of a BS are each comprised of an access zone and a relay zone. In the access zone of the DL subframe, a BS or RS transmits data to an MS. In the relay zone of the DL subframe, the BS transmits DL data, necessary to provide the MS with a relay service, to the RS. In the access zone of the UL subframe, the MS transmits data to the BS or RS. In the relay zone of the UL subframe, the RS transmits UL data, necessary to provide the MS with a relay service, to the BS.
The aforementioned system of FIG. 1 is possible in a case where a BS, an RS, and an MS all follow the same wireless system. However, a data transmission method of FIG. 1 cannot be used in a case where even any one of the BS, RS, and MS follows two or more wireless systems.
In general, communication systems are evolving by providing a high-speed data service as compared to a legacy system and solving issues on realization through a change of standards, etc. In this evolution process, a variety of systems can coexist within the same area depending on the degree of compatibility with a legacy system. For example, a new system that is more advanced than a legacy system can be installed in an area where an IEEE 802.16e system (i.e., a legacy system) is installed. The new system may support all services for a new MS as well as a legacy MS. In other words, there is a need for a frame structure that, if an MS following a legacy system and an MS following a new system coexist, can support a service of both MSs.